
The character and legend of Aeneas, which was first established in Homer’s Illiad, reappears in Virgil’s Aenied. Virgil drew Aeneas’ future role as the ancestor of the Romans from Achilleus’ rampage in the Illiad. In this scene, Aeneas, encouraged by Apollo, challenges Achilleus to a battle. During the battle Poseidon says:
“But why does this man, who is guiltless, suffer his sorrows
for no reason, for the sake of others’ unhappiness, and always
he gives gifts that please them to the gods who hold the wide heaven.
But come, let us ourselves get him away from death, for fear
the son of Kronos may be angered if now Achilleus
kills this man. It is destined that he shall be the survivor,
that the generation of Dardanos shall not die, without seed
obliterated, since Dardanos was dearest to Kronides
of all his sons that have been born to him from mortal women.
For Kronos’ son has cursed the generation of Priam,
and now the might of Aineias shall be lord over the Trojans,
and his sons’ sons, and those who are born of their seed hereafter. (20.297-308)”
This passage sets the basis for Virgil’s Aenied. It is evident Aeneas was destined to survive at Troy and will one day lead over its decedents. While researching I also found an interesting connection to why Virgil chose Aeneas as the founder of the Roman race:
“As the Romans came into contact - and conflict - with the Greeks in the third and second centuries B.C., they sought to link themselves with Greek legends, and gradually adopted Aeneas - an enemy of the Greeks - as an ancestor and a founder of a city, Lavinium, that was a precursor of Rome itself. In the Aeneid, Virgil elaborated upon these legends, reworked some of them, and organized them into a grand epic that stressed Aeneas’ role as the ancestor of the Roman people and linked his personal destiny with the historical destiny of Rome to become the seat of a great empire. At its core, though, is the hero whom Homer destined for survival in the Iliad (Virgil’s Aeneid: Introduction).”
The piety of Aeneas, attributed to him by Poseidon in the Illiad, develops into a defining characteristic throughout the Aenied. I also noted, that Virgil used the words of Poseidon as his own starting point for the Aenied. In the Illiad, Aeneas is described as a “guiltless” man who must “suffer his sorrows for no reason”. Similarly, Virgil begins the Aenied by saying, “Tell me, O Muse, the cause; wherein thwarted in will or wherefore angered, did the Queen of heaven drive a man, of goodness so wondrous, to traverse so many perils, to face to many toils.”
It is in these lines we are first introduced to Aeneas, described as a man of insignem pietate (Aenied 1.10). Later, I noticed that Aeneas introduces himself to the huntress by declaring, “I am the loyal/pious Aeneas” (“sum pius Aeneas”, Aenied 1.378). It appears as if Virgil uses Aeneas to portray the Roman hero, displaying the qualities of pietas and duty. He is a good man who is forced to suffer at the hands of a larger divine plan. Roman pietas consisted of three main duties: duty towards the Gods, duty towards country, and duty towards family/followers (Wikipedia). It is already evident that Aeneas has submitted himself to the will of the gods. From Jupiter’s prophecy we learn that Aeneas will rage a great war in Italy, crush proud nations, establish Latium, and found the Roman race. Reading ahead, I know that Aeneas’ pietas will cause him to leave Dido in order to continue to fulfill his destiny. This example provides evidence of his duty of country and the gods, but not to his family.

Curious, I decided to search the Internet for a peek ahead. From my research I learned that Virgil greatly explores the relationship between fathers and sons as the poem continues. Apparently, Aeneas had rescued his father, Anchises, and son, Ascanius, from Troy. The image of him departing with Ascanius, while carrying the Trojan ancestral gods in his arms and his father on his back, is the epitome of the three duties associated with pietas.
On a side note, I also found that many scholars believe Aeneas’s piety was a direct attempt by Augustus to establish himself as a pious ruler. Virgil had been commissioned by Augustus to write the Aenied. This would explain his obvious flattery of the Roman’s and the rulers during Jupiter’s speech. As Mr. O’Donnell put it, “he was sucking up to his commissioner.” Virgil may have in way alluded to Augustus through Aeneas. It heavily suggested that gods “work their ways” through humans. The people of Rome must accept their fate, just as Aeneas accepted his fate to found Rome, and Augustus’ fate to lead it. In a way, this gave Augustus an unquestionable god given power.
From what little we have already seen of the Aenied, and the additional information I have learned online, I can tell pietas will be a resounding theme. Its obvious importance will make it a likely AP question (2005 AP asked about it), so make sure to keep your eyes peeled for more supporting evidence!

Sources
1. http://vergil.classics.upenn.edu/comm2/legend/legend.html#pius
2. http://www.answers.com/topic/aeneid
3. Wikipedia
4. http://shell.cas.usf.edu/~demilio/2211unit3/vrglcint.htm
5. Loeb Translation